This application claims priority from Japanese Patent Application No. 2003-317923 filed Sep. 10, 2003, which is hereby incorporated by reference herein.
1. Field of the Invention
The present invention relates to a solder ball bonding method and a solder ball bonding device. In particular, the present invention relates to a solder ball bonding method and a solder ball bonding device that are suited for making fine bonding, such as bonding between a bonding pad that is formed on a magnetic head slider and a pad that is formed on a lead frame side.
2. Related Background Art
A connection method is conventionally known, with which electrodes that are objects to be bonded are placed close to each other, the electrodes are made to contact ball-shaped solder (hereinafter called solder ball), and heat and ultrasonic vibration are applied to the solder ball (so-called ultrasonic pressure welding), thus making an electrical connection between the electrodes.
Further, in addition to bonding by using pressure welding, a bonding method is also known in which a solder ball is disposed between the electrodes, and the solder ball is melted by using laser irradiation, thus making an electrical connection between the electrodes.
FIGS. 7A, 7B, and 7C are explanatory diagrams that show procedures for performing bonding between electrodes by melting the solder ball using laser irradiation. It should be noted that FIGS. 7A, 7B, and 7C are for bonding a bonding pad that is formed on a magnetic head slider and a pad that is formed on a lead frame side.
Referring to FIG. 7A, for bonding to this type of magnetic head, a slider 1 that configures the magnetic head and is an object to be bonded, and a flexure 2 that supports the slider 1, are both connected in advance by using an adhesive so that the electrodes are in mutual contact.
A bonding device 3 that bonds the slider 1 and the flexure 2 includes a suction nozzle 5 that suctions a solder ball 4, and a laser irradiation portion 6 that irradiates the solder ball 4 with a laser. The suction nozzle 5 and the laser irradiation portion 6 are fixed to a coupling block 7, and are moved reciprocatively between a magnetic head side and a solder ball supplying device 8 side by moving means (not shown).
When bonding the slider 1 and the flexure 2, first the bonding device 3 is moved to the solder ball supplying device 8 side, and the solder ball 4 is suctioned from the solder ball supplying device 8 by using the suction nozzle 5. The moving means is operated after the solder ball 4 is thus suctioned by the suction nozzle 5, conveying the solder ball 4 to an electrode 9 where electrodes of the slider 1 and the flexure 2 contact, as shown in FIG. 7B. Suctioning by the suction nozzle 5 is then stopped, and the solder ball 4 is then loaded onto the electrode 9. The moving means is once again operated after the solder ball 4 is loaded onto the electrode 9, moving the laser irradiation portion 6 to a position above the solder ball 4. The laser is then used to irradiate the solder ball 4 to melt the solder ball 4 and perform connection between the electrodes that are formed on the slider 1 and the flexure 2 (refer to JP 2002-25025 A, FIG. 6, for example).
Further, a bonding device having a laser light source disposed above the device, and having a connection element that is provided with a connection piece that supplies a solder ball on a side portion of the bonding device, is known as another solder ball bonding device. After being dropped into the connection element, the solder ball is melted by using the laser light source (refer to JP 11-509375 A, FIG. 1, for example).
In addition, a device having a three layer structure made from an arrangement mask, a shutter mask, and a supply mask is also known as another type of solder ball bonding device. By sliding the shutter mask that is sandwiched between the arrangement mask and the supply mask, a solder ball freely falls from the arrangement mask side to the supply mask side, thus supplying the solder ball onto a pad to make bonding (refer to JP 8-236916 A, FIG. 8, for example).
However, problems such as those described below exist with the solder ball bonding devices mentioned above.
More particularly, with methods of bonding objects by combining heating and ultrasonic vibration, an external force sufficient to perform pressure welding must be applied to the objects. For example, for a case where the bonding objects are a slider and a flexure that constitute a magnetic head, a receiving member that receives an external force must be provided to a back surface side in order to prevent deformation due to the external force. There is a problem as a result in that the number of device configuring members increases.
Further, with another bonding device in which the suction nozzle 5 and the laser irradiation portion 6 are provided, after the solder ball 4 is loaded onto the electrode 9 by using the suction nozzle 5, the solder ball 4 cannot be held at a bonding device side. Therefore, there is a danger that the solder ball 4 becomes loaded onto the electrode 9 will shift position due to an external disturbance. Accordingly, there is a problem in that additional means for holding the solder ball 4 has to be provided in addition to a manufactured product itself and the bonding device.
Furthermore, the bonding devices described above, that is the bonding devices that use pressure welding, the bonding devices that use the suction nozzle 5 and the laser irradiation portion 6, and the bonding devices that use the connection element having the laser light source and the bonding piece, perform bonding to a single electrode. For cases in which a plurality of electrodes exist, the series of processes described above must be repeated for each of the plurality of electrodes, and it is difficult to increase the efficiency of the manufacturing processes.
In addition, although it is possible to arrange a plurality of solder balls in a plurality of holes with the devices having the three-layer structure made from the arrangement mask, the shutter mask, and the supply mask, bonding cannot be performed by conveying isolated specific solder balls to specific locations.